ACP: composer-2.5 model is always used when Auto is selected

Where does the bug appear (feature/product)?

Cursor CLI

Describe the Bug

I use neovim with agentic.nvim (ACP client)

When I select Auto model Cursor ACP eventually uses composer-2.5

Steps to Reproduce

  1. Choose Auto model
  2. Make a request
  3. Open https://cursor.com/dashboard/usage and see composer-2.5 model was used in the last turn

Expected Behavior

auto model is used and displayed on the dashboard correctly

Operating System

MacOS

Version Information

CLI Version 2026.06.04-5fd875e
Model Composer 2.5
Subscription Tier Enterprise
OS darwin (arm64)
Terminal ghostty
Shell zsh

Additional Information

=====

[2026-06-09 23:23:30] [agentic.acp.acp_client:234] request: {
id = 7,
jsonrpc = “2.0”,
method = “session/set_config_option”,
params = {
configId = “model”,
sessionId = “24fed669-5507-477f-ab46-ce4043ed7c41”,
value = “default
}
}

=====

[2026-06-09 23:23:31] [agentic.acp.acp_client:282] Cursor Agent ACP response: {
id = 7,
jsonrpc = “2.0”,
result = {
configOptions = { {
category = “mode”,
currentValue = “ask”,
description = “Controls how the agent executes tasks”,
id = “mode”,
name = “Mode”,
options = { {
description = “Full agent capabilities with tool access”,
name = “Agent”,
value = “agent”
}, {
description = “Read-only mode for planning and designing before implementation”,
name = “Plan”,
value = “plan”
}, {
description = “Q&A mode - no edits or command execution”,
name = “Ask”,
value = “ask”
} },
type = “select”
}, {
category = “model”,
currentValue = “default”,
description = “Controls which model variant is used for responses”,
id = “model”,
name = “Model”,
options = { {
name = “Auto”,
value = “default
}, {
name = “Composer 2.5”,
value = “composer-2.5[fast=false]”
}, {
name = “Opus 4.8”,
value = “claude-opus-4-8[thinking=true,context=300k,effort=high,fast=false]”
}, {
name = “GPT-5.5”,
value = “gpt-5.5[context=272k,reasoning=medium,fast=false]”
}, {
name = “Sonnet 4.6”,
value = “claude-sonnet-4-6[thinking=true,context=200k,effort=medium]”
}, {
name = “Codex 5.3”,
value = “gpt-5.3-codex[reasoning=medium,fast=false]”
}, {
name = “Opus 4.7”,
value = “claude-opus-4-7[thinking=true,context=300k,effort=xhigh,fast=false]”
}, {
name = “GPT-5.4”,
value = “gpt-5.4[context=272k,reasoning=medium,fast=false]”
}, {
name = “Opus 4.6”,
value = “claude-opus-4-6[thinking=true,context=200k,effort=high,fast=false]”
}, {
name = “Opus 4.5”,
value = “claude-opus-4-5[thinking=true]”
}, {
name = “GPT-5.2”,
value = “gpt-5.2[reasoning=medium,fast=false]”
}, {
name = “Gemini 3.1 Pro”,
value = “gemini-3.1-pro
}, {
name = “GPT-5.4 Mini”,
value = “gpt-5.4-mini[reasoning=medium]”
}, {
name = “GPT-5.4 Nano”,
value = “gpt-5.4-nano[reasoning=medium]”
}, {
name = “Haiku 4.5”,
value = “claude-haiku-4-5[thinking=true]”
}, {
name = “Sonnet 4.5”,
value = “claude-sonnet-4-5[thinking=true,context=200k]”
}, {
name = “Codex 5.2”,
value = “gpt-5.2-codex[reasoning=medium,fast=false]”
}, {
name = “Codex 5.1 Max”,
value = “gpt-5.1-codex-max[reasoning=medium,fast=false]”
}, {
name = “GPT-5.1”,
value = “gpt-5.1[reasoning=medium]”
}, {
name = “Gemini 3 Flash”,
value = “gemini-3-flash
}, {
name = “Codex 5.1 Mini”,
value = “gpt-5.1-codex-mini[reasoning=medium]”
}, {
name = “Sonnet 4”,
value = “claude-sonnet-4[thinking=false,context=200k]”
}, {
name = “GPT-5 Mini”,
value = “gpt-5-mini
}, {
name = “Gemini 2.5 Flash”,
value = “gemini-2.5-flash
} },
type = “select”
} }
}
}

=====

[2026-06-09 23:23:33] [agentic.acp.acp_client:234] request: {
id = 8,
jsonrpc = “2.0”,
method = “session/prompt”,
params = {
prompt = { {
text = “Hello!”,
type = “text”
} },
sessionId = “24fed669-5507-477f-ab46-ce4043ed7c41”
}
}

=====

[2026-06-09 23:23:39] [agentic.acp.acp_client:282] Cursor Agent ACP response: {
id = 8,
jsonrpc = “2.0”,
result = {
stopReason = “end_turn”
}
}

=====

Does this stop you from using Cursor

No - Cursor works, but with this issue

Hi Maksym,

Thanks for the detailed logs! Good news — this is expected behavior, not a bug.

Auto isn’t a model itself; it selects the best available model for each request, and Composer 2.5 is one of the models that can be used by Auto. The usage dashboard intentionally shows the actual model that ran (so composer-2.5 after an Auto request just tells you what Auto chose for that turn). This matches how Auto works in the Cursor IDE too.

Your ACP setup is also working correctly — the logs show Auto (value: "default") selected and honored.

If you’d like a guaranteed model every time, just pick it explicitly (e.g., Composer 2.5, Opus 4.8) instead of Auto.

Hope that clears it up :smiley:


The turns in red were triggered within the Cursor IDE, the most recent 2 using ACP.

I was a bit confused.

Thanks for the quick response!